Process of obtaining phosphatides from soap stock



Patented Dec. 5, 1939 um'rao STATES PATENT OFFICE PBDCESS F OBTAININGPHOSPHATIDES FROM SOAP STOCK 1 Benjamin H. Thurman, Bronxville, N. Y.,assignor to Refining, Inc., Reno, Nev., a. corpora tion of Nevada NoDrawing. application January 21, 1939, Serial 'No. 252,212

customarily obtained by treating an oil with 8 caustic alkalies oralkaline carbonates or phosphates or other reagents that will saponifythe free fatty acids in the oil and then separating the soap stock fromthe oil. While the phosphatides of the higher quality more highlysaturated oils,

10 such as cottonseed or corn, sesame or rape seed oil, have moredesirable qualities and greater usefulness, the process of the presentinvention is applicable to the recovery of the phosphatides contained inthe soap stock from the alkali refin- 16 ing of more highly unsaturatedoils such as soya bean oil or linseed oil.

It has heretofore been known that says. beans contained vegetablelecithin or phosphatides which could be obtained'by direct extraction of20 the beans with a lecithin solvent. This constituted the sole sourceof commercial vegetable lecithin as it was not known that substantialamounts of phosphatides were present in recoverable form in vegetableoils separated from the beans or seeds by the usual processes ofproducing oil, for example', by hot or cold pressing operations. Thepresence of phosphatides in vegetable oils and methods of recoveryof'the phosphatides from the oil are disclosed in my copendingapplication 0 Serial No. 6,446, filed February 14, 1935 when suchvegetable oils arerefined with alkaline re- 1 agents the free fattyacids of the oil are neutralized with an equeous solution of causticsoda or other strong alkali usually under high tempera- '5 tureconditions. The alkali not only neutralizes the free fatty acids to formsoap but attacks neutral glycerides to form soap and glycerine. Gums andcoloring matter in the oil are precipitated and the resulting soap andother precipi- 48 tated materials are separated from the oil by settlingor centrifugal separation along with water, excess alkali, and entrainedneutral oil as soap stock.

This soap stock is a malodorous and darkly 5 colored product, in whichthe gums were formerly regarded as undesirable impurities, and which wasformerly believed to be entirely worthless except for employment in lowgrade soaps after extensive purification. treatment. so The phosphatidesconstitute part of the gums and are also subject to attack by the alkalito form decomposition products. The chemistry of the reaction between anand phosphatides under refining conditions iscomplex and not fully 5established. As lecithin can [be completely hydrolized to produceglycerol-phosphoric acid, fatty acids, and choline, it was reasonable toassume that the phosphatides were substantially completely destroyedunder the drastic treating conditions during refining. I have, however,5 found that the soap stock obtained from vegetable oils in the usualway contains up to as high as 10% of recoverable phosphatides. A part ofthe phosphatides of the original oil may be destroyed or the chemicalcomposition of all or a 10 i portion of the phosphatides may bealteredduring the refining process but the phosphatides recovered from the soapstock, in accordance with the present invention, appear to retain theirdesirable qualities.

By the present invention the phosphatides may e removedin large measureor substantially entirely from the soap stock in such a way that they donot contain an appreciable or seriously objectionable amount ofinjurious impurities or dis- 2o coloring materials.

In carrying out the invention the soap stock may be treated with any ofthe well known fat solvents, such as petroleum ether, ethyl ether,benzene, ethylene dichloride, trichloroethylene, 25 carbontetrachloride, etc. Thesolution may then be separated from the soapstock residue by decantation, centrifuging or filtering and the solventis evaporated or distilled off. leaving the phosphatides as a residue.

Or, the soap stockmay be treated with a solvent ,for the soap stock.Acetone, for example, may be used for this purpose as it will dissolveand remove the soap, free oil and water leaving the phosphatides as aresidue when the solution is filtered or centrifuged; Other soapsolvents, such as methyl acetate, for example, in which the phosphatidesare' insoluble or difliculty soluble, may be used instead of acetone forthis purpose. 40

The following are given as specific examples of carrying out theinvention, but it is.to be understood that these examples arenot-exhaustive and that the invention is not restricted to the treatmentof soap stock from any particular oil or to 5 any particular solvent orproportion mentioned or to the temperature or time specified. 7

Example 1.--Approximately five partsby volume of petroleum ether wereadded to one part of cottonseed oil soap stock obtained by saponifyingthe fatty acids in cottonseed oil with-soda ash. The mixture -wasagitated or stirred for' about 20 minutes at room temperature(approximately F.) and then filtered. The ether was evaporated of! at atemperature of about 100- I6 200 F. leaving a residue which was about ofthe weight of the soap stock that was extracted.

Example 2.-About one part by volume of cottonseed oil soap stock wasagitated with five parts of acetone for a few minutes at roomtemperature and the mixture was filtered. The solids left on the filterwere for the most part phosphatides and amounted to about 10% of theweight of the soap stock.

. The solid content of the mass containing phosphatides that is obtainedfrom the soap stock contains about or of the valuable phosphatides fromwhich a large portion or substantially all of the remaining solids ordeleterious matter can beremoved. The remaining purified phosphatidesfrom the more highly saturated oils are of such a character that they donot have an objectionable taste or odor and do not become rancid for along time even when exposedto air. Certain ingredients which appear toaid in preserving the phosphatides may, have been removed from the soapstock with the phosphatides and are not removed from the phosphatidesduring the purification step. The deleterious impurities may be removedfrom the phosphatide mass or residue by washing the phosphatides orsolids with water, or an aqueous sodium chloride solution may be usedinstead of water for washing the phosphatides. About 10% of sodiumchloride in the water has been found to be satisfactory. An aqueous saltsolution apparently has a solvent action on some of the globulin andalbuminoid substances in the phosphatide mass so that' they are removedduring the washing step. Also, the remaining insoluble phosph'atides areleft in small particles. The phosphatides may be washed repeatedly withwater containing salt. The phosphatides or remaining product may bedried. The drying is preferably done in a vacuum with a temperature notexceeding 70 C. When the phosphatides have been obtained by means ofsolvents for the phosphatides and evaporating the solvents, the driedproduct may be washed with acetone to remove acetone soluble materials,such as fatty acids, coloring materials and small amounts of otherundesirable substances. The acetone'may be distilled ofi' while the airis excluded from the product. By way of example, the purified driedmaterial from cottonseed oil soap stock is yellow and in the form of apowder while that from corn oil soap stock is a gray waxy material.

It has also been found that water can be used for washing thephosphatides without having salt dissolved in it, provided the pH of thewater is kept sumciently low, say about pH 3 to pH 4.5, and preferablythe lower value, to prevent emulsification. Chloride ions appear to beparticularly advantageous in preventing emulsification, although otheracids and acid salts, such as tartaric, citric, sulphuric acids andsodium salts and sodium acid salts, for examplawhich will lower the pHof the solution can be used. However, hydrochloric acid has thus farbeen found to be the most satisfactory for this pur- The purified dryproduct may be dissolved in a non-solidifying oil, such as sunfloweroil, sesame oil, or soya bean oil and the substances that are insolublein these oils may be centrifuged or filtered out. The percentage of oilsused for dissolving the product may be 40% or more of the weight of theproduct that is dissolved in the oil.

Phosphatides from the soap stock of the less unsaturated oils, such ascottonseed oil or corn oil, have the most useful properties as theycontain no linolenic acid radicals and are more stable. By way ofexample, some of the characteristics which distinguish the phosphatidesor product obtained, as described above. from cottonseed oil, fromsimilar products are as follows:

(a) This product contains approximately the same percentage ofphosphorus. namely about 1.8%, calculated on a dry basis, as theprecipitate that precipitates out of the 011 after it has, been allowedto stand for a long time without the addition of a reagent. V

(b) The iodine number of the purified product is approximately 60, whilethe iodine number of the purest vegetable-lecithin products now known isabout 90.

(0) Fatty acids obtained from this purified product or phosphatides havean iodine number of about while the iodine number of cottonseed oil isabout 108 and the iodine number of soya bean oil, as well as the fattyacids from lecithin obtained therefrom, is about 125. The low iodinenumber of the product of this invention and the fatty acids obtainedfromit probably explains, at least in part, why the product of thisapplication will keep such along time or has very little tendency toabsorb air and become rancid.

(d) The product or phosphatides of this .invention may be dissolved inhigh boiling oils, such as sunflower seed oiland heated to 440 F.without c anging color very much and without having a very noticeableamount of objectionable odor or taste imparted thereto, while lecithinobtained from soya beans and heated in the same way has imparted to it avery dark or almost black color and a very nauseating odor andunpalatable taste, resembling the odor of fish-or paint.

(e) A trace of gossypol or rafflnose has been found in the phosphatides,but is not present in suillcient amounts to interfere with theedibleness of the phosphatides.

Phosphatidesobtained from the soap stock of other of the lessunsaturated oils, such as corn oil, have properties very similar tothese of the cottonseed oil phosphatides described above. The purifiedphosphatides obtained from such oils are useful for many purposes, someof which a may be mentioned; as an agent for reducing the viscosity ofsugar, chocolate and fat coatings; a small amount, say 0.3% thereof,added to chocolate prevents the same from blooming after several hourseven in warm weather; about onehalf of 1% thereof added to vegetableoils greatly decreases the tendency of these oils to become rancid evenat temperatures up to F.

I or higher over an extended period of time; about 1% or less thereofadded to dressings, such as mayonnaise. materially increases the keepingqualities of the same and prevents or greatly retards rancidity; lessthan 1% thereof added to margarine'prevents' the same from foaming orspatter-ing when heated, thus permitting food, such as eggs, to bebrowned when fried therein; less than 1% added to deep frying oils orfats prevents or greatly retards rancidity and acquisition of badflavors or odors even at temperatures somewhat above 400 F.; a smallamount thereof added to fatsused in making caramels improves the qualityof the caramels without imparting any objectionable taste.

It has been found that'mayonnais'e containing soya' bean oil which wouldbecome rancid and develop a characteristic odor in a few days willremain fresh when about 0.3/10ths percent of the product or phosphatidesof this invention is added. This product seems to act as an antioxidantor at least prevents development of the objectionable odor or flavor inthe soya bean oil. This may possibly be due to the prevention of theaction of enzymes or bacteria in the soya bean oil used in makingmayonnaise dressing. When about 0.1% of this product is added to butterit prevents formation of strong odors even when the butter is exposed tothe atmosphere for a long time and it also prevents water from leakingout of the butter, probably because it is a good emulsifying agent forthe butter. This product is also valuable as an apparent anti-oxidant inthe manufacture of rubber, as well as an excel-'- lent anti-oxidant whenput in linseed oil-varnish that is to be used for painting rubber goods.

The addition of even less than 1% of the product to fats or oils thatare used for frying vegetable products greatly reduces the tendency ofthese fats or oils to split and form products that are characteristic ofoverheated fats, thus imparting substances to the food products thatwould, cause them to become rancid. Food products, such as potato chipsthat have large surfaces are especially prone to become rancid veryrapidly by oxidation. The use of the product of this invention in fatsor oils for frying such vegetables protects the products and permits thesame fatty oil to be used repeatedly for frying them.

This application is a continuation in part of my copending applicationSerial No. 688,361,

filed September 6, 1933, and of my copendingv application Serial No.6,446, filed February 14, 1935, now Patent No. 2,150,732, which is inturn a continuation in part of my applications Serial No.-644,13'7,filed November 23, 1932 and Serial bio. 676,932, filed June 21, 1933. fi

I claim:

1. The process ofrecovering phosphatides which comprises treatingcottonseed oil soap 1 stock with a fat solvent which will dissolvephosphatides and in which soap is substantially insoluble, removingthesolution, evaporating the solvent and washing the residue with anaqueous solution having a pH of not more than about 3.

2. The process of recovering phosphatides which comprises treatingcotton seed oil-soap- 5, stock with a fat solvent in which phosphatidesare soluble and soap stock is substantially insoluble, removing thesolution, evaporating the solvent and washing the residue with anaqueous solution containing chloride ions and having a tides and inwhich soap is substantialfy insoluble, removing the solution,evaporating the solvent pH of not more than about 3. a

3. The process of recovering phosphatides,-

ing-vegetable oils and containing a material consisting essentially ofphomhatides and a material consisting essentially of soap, with asolvent for only one of said materials to form a solution of said one ofsaid materials, separating the undissolved material from said solutionto separate said soap from said phosphatides, and further treating thematerial containing said phosphatides to purify said phosphatides.

4. The process er recovering phosphatides, which comprises, treating.soap stock, resulting from the alkali refining of phosphatide containingvegetable oils and containing a material consisting essentially ofphosphatides and a material containing essentially soap, with a solventwhich will dissolve said material containing, phosphatides to form asolution thereof without dissolving said soap, separating. theundissolved material containing soap from said solution to separate saidsoap from said phosphatides and further treating said solution to purifysaid phosphatides.

5. The process ofv recovering phosphatides, which comprises, treatingsoap stock resulting fromthealkalirefiningofcottonseedoiland I from thealkali refining of cottonseed oil andcontaining phosphatides and soapwith a solvent which will dissolve said phosphatides to form a solutionthereof without dissolving said soap, separating the undissolvedmaterial from said solution to separate said soap from said phosphatidesand further treating said solution topurify said phosphatides. 1

7. The process of recovering phosphatides,

which comprises, treating soap stock, resulting w from the alkalirefining of phosphatide containing vegetable oils and containing amaterial consisting essentially of phosphatides and a materialconsisting essentially of soap, with a solvent for only one of saidmaterials to form a solution of said one of said materials, separatingthe undissolved material from saidsolution to separate said soap fromsaid phosphatides, and washing solvent free, separated phosphatides withan aqueous solution having a pH between about 3 and 4.5 to furtherpurify said phosphatides.

8. The process of recovering phosphatides, which comprises, treatingsoap stock, resulting from the alkali reflningof phosphatidecontain-ling vegetable oils and containing a material consistingessentially of phosphatides and a material containing essentially soap,with a solvent which will dissolvesaid material containing phosphatidesto form a solution thereof without dissolving said soap,evaporating-said solvent and -washing the residue with an aqueoussolution having a pH of between about 3 and 4.5 to further purifysaidphosphatides.

9. The process of recovering phosphatides I which comprises treatingvegetable oil soap stock with a fat solvent which will dissolvephosphaand washing the residue with an aqueous solution having a pH ofnot more than about 3. v

10. The process of recovering phosphatides which comprises treatingvegetable oil soap stocii with a fat solvent in which phosphatides aresoluble and soap stock is substantially insoluble, removing thesolution, evaporating the solvent and washing the residue with anaqueous solution containing chloride ions and having a pH of not morethan about 3.

11. 'The process of recovering phosphatides from soap stock whichcomprises the steps of: subjecting vegetable oils containingphosphatides.

10 free fatty acids and other impurities to treatment with an alkalinerefining reagent to reactv'with the free fatty acids to form soap stockcontaining said phosphatides without destruction to said phosphatides,thereafter subjecting said soap stock with the phosphatides containedtherein to treatment with a solvent capable of separating the soap stockfrom the phosphatides and thereatfotzi separating the phosphatides fromsaid soap 5 12. The process as defined in claim 11 in which theseparated phosphatides are subjected to purification.

V BENJAMIN H. THURMAN.

